Windows Theme Monitor

A comprehensive Windows desktop application that monitors Light/Dark theme changes and provides theme persistence functionality.

Features

Core Functionality

• Real-time Theme Monitoring: Detects changes to Windows Light/Dark theme settings
• Process Detection: Identifies which process or service triggered theme changes
• Comprehensive Logging: SQLite-based logging system with detailed change history
• Theme Persistence: Enforces selected theme by continuously resetting registry values
• System Tray Integration: Runs in background with system tray icon
• Auto-startup: Optional Windows startup integration

Modern UI

• PySide6-based Interface: Modern, responsive GUI with tabbed interface
• Dashboard Tab: Current theme status and persistence controls
• Logs Tab: Sortable, filterable view of all theme changes
• Settings Tab: Startup configuration and log management

Technical Features

• Registry Monitoring: Monitors HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Themes\Personalize
• Background Service: Efficient background monitoring without impacting performance
• Portable Executable: Single-file executable via PyInstaller
• No Admin Rights Required: Runs with standard user privileges

Installation

Option 1: Run from Source

1. Ensure Python 3.11+ is installed
2. Run install.bat to install dependencies
3. Execute: python main.py

Option 2: Build Executable

1. Install dependencies: pip install -r requirements.txt
2. Install PyInstaller: pip install pyinstaller
3. Build: pyinstaller --onefile --noconsole --icon=assets/icon.ico main.py
4. Run the executable from the dist/ folder

Usage

Dashboard Tab

• View current theme mode (Light/Dark)
• Enable/disable theme persistence
• Select preferred theme for persistence mode
• Manual theme switching buttons

Logs Tab

• View chronological list of all theme changes
• Sort by timestamp, theme mode, or source process
• Export logs to CSV for analysis
• Real-time updates as changes occur

Settings Tab

• Configure Windows startup behavior
• Manage log database (clear logs)
• View application information

System Tray

• Double-click tray icon to show main window
• Application continues running when main window is closed
• Right-click for quick access menu (if implemented)

Persistence Mode

When enabled, Persistence Mode:

1. Monitors theme settings every 500ms
2. Automatically resets theme if changed externally
3. Logs all enforcement actions
4. Effectively "locks" the theme to your preference

Use Cases:

• Prevent applications from changing your theme
• Override Group Policy theme settings
• Maintain consistent theme across all applications
• Block unwanted theme changes from system updates

Technical Details

Registry Keys Monitored

• AppsUseLightTheme: Controls app-level theme (0=Dark, 1=Light)
• SystemUsesLightTheme: Controls system-level theme (0=Dark, 1=Light)

Database Schema

SQLite database stores:

• Timestamp of change
• New theme mode (Light/Dark)
• Source process name
• Detailed change information

Performance

• Minimal CPU usage (< 1% on modern systems)
• Small memory footprint (< 50MB RAM)
• Efficient registry monitoring
• Non-blocking UI operations

Troubleshooting

Common Issues

1. Registry Access Denied: Ensure running as standard user, not restricted account
2. Theme Not Changing: Check Windows version compatibility (Windows 10/11)
3. Persistence Not Working: Verify no Group Policy restrictions
4. Build Failures: Update PyInstaller and dependencies

Logs Location

Application logs and database stored in: C:\Users\<Username>\AppData\Roaming\ThemeMonitor\

System Requirements

• Windows 10 version 1903+ or Windows 11
• Python 3.11+ (for source execution)
• 50MB free disk space
• No administrator privileges required

Development

Project Structure

ThemeMonitor/
├── main.py                 # Application entry point
├── theme_monitor.py        # Core monitoring logic
├── service.py             # Background service wrapper
├── ui/
│   ├── __init__.py
│   └── main_window.py     # PySide6 main window
├── assets/                # Icons and resources
├── requirements.txt       # Python dependencies
├── build_instructions.txt # Build guide
└── install.bat           # Windows installer

Key Classes

• ThemeMonitor: Core functionality for registry monitoring and persistence
• ThemeService: Service wrapper for background operations
• ThemeMonitorWindow: Main PySide6 UI window
• StartupManager: Windows startup registry management

License

This project is provided as-is for educational and personal use.

Contributing

This is a demonstration project. For production use, consider:

• Enhanced process detection using ETW (Event Tracing for Windows)
• Digital signing for the executable
• MSI installer creation
• Additional theme-related registry keys monitoring
• Group Policy integration